Prevention of vole damage in organic pomiculture

Vole damage is one of the most difficult phytosanitary problems to solve in organic pomiculture. A survey conducted in 2002 among German fruit growers showed that 90 % of the farms suffered from this damage. The water vole (A. terrestris) revealed to be the main pest in 80 % of the orchards. 61 % of the farmers announced a high interest in the development of new preventive and control methods. To stop immigration of voles into orchards a mechanical barrier system was developed and tested at two study sites in Baden-Wuerttemberg and Rhineland-Palatinate. At each location barrier systems with wire mesh (mesh size 10 mm) and polyolefine-foil were installed arround two 0.7 ha study plots. Two unprotected plots were used as a control. The barriers were anchored 20 cm deep into the soil. 30 cm of the material protruded over the surface. Automatic gates were installed for the entrance of vehicles. 4 persons needed approximately one day to install a barrier around a plot with the size of 1 ha. Not only was the wire mesh cheaper than the foil, it was permeable for wind, water and small beneficial organisms. After installing the barrier systems, voles were removed from all plots. Snap trap boxes were ranged along the outside of the barriers to catch migrating voles. A total of 33 water voles and 1263 common voles (M. arvalis) were captured on both study sites from October 2002 to November 2003. During the study period a total of 5 water voles immigrated into the first control plot and 6 settled into the other plot. Four water voles entered two of the barrier protected plots by using fresh mole galleries. The other protected plots stayed free from water voles. Simultaneous to the field studies, trials in two enclosures were carried out in Muenster. The barriers kept all water voles outside the protected plots. The results showed a high efficacy of the developed barrier system

How expensive is vole damage?

Vole species, especially Arvicola terrestris and Microtus arvalis cause significant economical damage in organic pomiculture by gnawing the root system of trees. The importance of voles as pest organisms is well known. Nevertheless, the estimation of financial loss caused by voles is difficult for German fruit growers. We conducted a survey among organic fruit growers to get data on kind and amount of annual damage. Using the available publications and official statistics we calculated economical values of organic apple trees for different types of orchard processing and tree ages. Furthermore we calculated the number of trees lost due to voles in one year

Results for Channel Error Profiles for DECT

This letter presents the main statistical characterization of the underlying error process obtained in the case of the Digital European Cordless Telecommunications (DECT) radio system. By simulation of the transmission link, error sequences are generated for different channel parameters. Relevant statistics are then computed for the purpose of efficient channel coding design and evaluation

Abwehr von Wühlmausschäden im ökologischen Obstbau mit Hilfe von Migrationsbarrieren

Sowohl im integrierten als auch im ökologischen Obstbau gelingt eine dauerhafte Abwehr von Wühlmausschäden mit den zur Verfügung stehenden Mitteln nur unzureichend. Nach den Ergebnissen einer Umfrage, für die 279 Rückmeldungen ausgewertet wurden, sind 90 % der deutschen Obstbaubetriebe von Wühlmausschäden betroffen. Hauptschadensverursacher ist die Schermaus (Arvicola terrestris), die für Schäden auf 80 % der Flächen verantwortlich gemacht wird

Swirl Boundary Layer at the Inlet of a Rotating Circular Cone

International audienceWhen a fluid enters a rotating pipe, a swirl boundary layer with thickness of $δ_S$ appears at the wall and interacts with the axial momentum boundary layer with thickness of $δ$. The swirl is produced by the wall shear stress and not due to kinematic reasons as by a turbomachine. In the center of the pipe, the fluid is swirl-free and is accelerated due to axial boundary layer growth. Below a critical flow number $ϕ < ϕ_c$, there is flow separation, known in the turbomachinery context as part load recirculation. Previous work analyses the flow at the inlet of a rotating circular pipe. For a systematic approach to a turbomachine, the influence of the turbine's and pump's function, schematically fulfilled by a diffuser and a nozzle, on the evolution of the swirl and flow separation is to analyse. The radius of the rotating pipe depends linearly on the axial coordinate, yielding a rotating circular cone. The swirl evolution depends on the Reynolds number, flow number, axial coordinate and apex angle. The influence of the la er is the paper's main task. The circumferential velocity component is measured applying 1D Laser Doppler Anemometry to investigate the swirl evolution

Magneto-Optical Spectrum Analyzer

We present a method for the investigation of gigahertz magnetization dynamics of single magnetic nano elements. By combining a frequency domain approach with a micro focus Kerr effect detection, a high sensitivity to magnetization dynamics with submicron spatial resolution is achieved. It allows spectra of single nanostructures to be recorded. Results on the uniform precession in soft magnetic platelets are presented.Comment: 5 pages, 7 figure

Abwehr von Wühlmausschäden im ökologischen Obstbau

Wühlmausschäden sind weit verbreitet und gehören zu den nur schwer lösbaren Pflanzenschutzproblemen im ökologischen Landbau. Nach einer Umfrage des Institutes für Nematologie und Wirbeltierkunde der Biologischen Bundesanstalt für Land- und Forstwirtschaft (BBA), im Jahre 2002 waren 90 % der befragten Obstbaubetriebe von Wühlmausschäden betroffen. Als Hauptschadensverursacher treten vor allem die Schermaus (Arvicola terrestris ), auch große Wühlmaus genannt, und die Feldmaus ( Microtus arvalis) auf. Mit den wenigen zur Verfügung stehenden Mitteln erreicht aber nur ein Bruchteil der ökologisch wirtschaftenden Betriebe einen akzeptablen Bekämpfungserfolg. Von Wissenschaft und Industrie werden viele Anstrengungen unternommen, um bekannte Abwehrmaßnahmen zu verbessern und neue Präparate sowie Methoden zu entwickeln. Dazu werden die Lebensweise und in letzter Zeit vor allem das sehr komplexe Verhalten von Wühlmäusen intensiv untersucht. In diesem Merkblatt werden die derzeit möglichen und angewandten Bekämpfungs- und Abwehrmaßnahmen für den ökologischen Obstbau sowie deren Erfolgsaussichten vorgestellt. Verschiedene Hinweise sollen helfen, die Wühlmausabwehr effizienter zu gestalten. Das Merkblatt richtet sich in erster Linie an Obstbauern und Obstbauberater. Aber auch Baumschulbetriebe, Gemüsebauern, kommunale Einrichtungen und Gartenbesitzer werden Anregungen für die Lösung von Wühlmausproblemen finden

Migrationsbarrieren gegen Wühlmäuse – Erfahrungen aus 3 Jahren Praxiseinsatz

In der landwirtschaftlichen Praxis wird die Wühlmausbekämpfung vorrangig mit Fraßködern, Fallen und Begasungsgeräten durchgeführt. Um die Besiedlung wühlmausfreier Flächen zu verhindern werden seit 2002 Migrationsbarrieren in der obstbaulichen Praxis erfolgreich erprobt

Entropy analysis of Boolean network reduction according to the determinative power of nodes

Boolean networks are utilized to model systems in a variety of disciplines. The complexity of the systems under exploration often necessitates the construction of model networks with large numbers of nodes and unwieldy state spaces. A recently developed, entropy-based method for measuring the determinative power of each node offers a new method for identifying the most relevant nodes to include in subnetworks that may facilitate analysis of the parent network. We develop a determinative-power-based reduction algorithm and deploy it on 36 network types constructed through various combinations of settings with regards to the connectivity, topology, and functionality of networks. We construct subnetworks by eliminating nodes one-by-one beginning with the least determinative node. We compare entropy ratios between these subnetworks and the parent network and find that, for all network types, the change in network entropies (sums of conditional node entropies) follows a concave down decreasing curve, and the slightest reductions in network entropy occur with the initial reductions which eliminate the nodes with the least determinative power. Comparing across the three network characteristics, we find trends in the rates of decrease in the entropy ratios. In general, the decline occurs more slowly in networks with degree values assigned from a power-law distribution and canalyzing functions of higher canalization depth. We compare results of the determinative-power-based reduction with those of a randomized reduction and find that, in forming subnetworks with maximal network entropy, the determinative-power-based method performs as well as or better than the random method in all cases. Lastly, we compare findings based on this conditional-entropy-based calculation of network entropy with those of an alternative calculation using simple sums of (independent) node entropies to demonstrate the vast differences resulting from the two approaches